Troubleshooting power issues with 7720

[jeamn]

I've been having issues for a while now that I *think* might be a bad motherboard VRM, but I'm still hoping it's not, and maybe battery related.  What I'm seeing is this.

 

• With a power adapter plugged in when under heavy gaming work related tasks, the CPU will occasionally throttle down to minimum clock settings, this in turn seems to throttle the GPU.  After a few minutes, it seems to recover and clock back up.  Using hwinfo64, there isn't any thermal throttling.  it stays relatively cool (around 70-80C) for a i7-7920hq.  GPU is also cool.
• When on battery, under any sort of load, (but especially when the GPU is active), it shuts down without warning.  The laptop will run under battery for many hours under light load, however.
• Once it occurs, the machine will not boot again until a power adapter is plugged in.  Pressing the power button does nothing.
• No thermal events reported in the BIOS.
• It seems to be unrelated to battery charge level.  (Eg, happens at whatever the current battery charge level is at, whether it's 25% or 100%)
• Symptoms occur under Win10 and Linux.

 

Things that I've tried so far

• Different power adapters (I have an OEM and a 330w Alienware brick)
• Different dGPUs.  I've swapped a p4000 and p3000 and it occurs the same with both
• Different batteries.  I tried a couple cheap ebay batteries with same result.  They have  bad reputation, so I also tried a used OEM battery with the same result.  

 

Is there anything else I should check or try to swap out before I pull the motherboard (or really get desperate and buy a new OEM battery)?  Could bad memory cause issues like this?

 

Also, in a pinch, are 7710 motherboards compatible?  I thought I'd read that they were practically identical.

 

[jeamn]

Also, if one were to try to purchase an OEM battery, where can you do it?  I can't find it on Dell's site and all the major e-commerce sites seem to have a variety of "offical" Dell batteries from $40 up to $120.  I assume some are counterfeit or re-labeled.  Is there any reputable dealer to purchase a battery from and be assured that it's actual OEM quality?

 

[Aaron44126]

I believe 7710 motherboards are compatible.  Find some photos and check the screw hole positions and make sure that they are the same, and you should be good.  (I know a couple of users upgraded Precision 7510 to 7520 by swapping out the motherboard.  I don't remember hearing about the 77X0 systems but I'd think it would be the same.)

 

Most stuff should be compatible but under Windows you'd need a NVIDIA INF mod to get a Pascal GPU to work.

 

Regarding the issue...  With just the top bullet, I'd suggest trying a different PSU if you haven't already.  But with that other stuff, and given that you've already replaced the battery...  Yes, I'm worried about your motherboard.

[jeamn]

On 9/13/2022 at 9:39 AM, Aaron44126 said:

I believe 7710 motherboards are compatible.  Find some photos and check the screw hole positions and make sure that they are the same, and you should be good.  (I know a couple of users upgraded Precision 7510 to 7520 by swapping out the motherboard.  I don't remember hearing about the 77X0 systems but I'd think it would be the same.)

 

Most stuff should be compatible but under Windows you'd need a NVIDIA INF mod to get a Pascal GPU to work.

 

That's a good point.  I was just thinking about it from cpu-wise, since both 7710s and 7720s shipped with I7-6820HQ as an option.  But yeah, I guess all the firmware would be downgraded as well.  At that point, I'm basically just transferring my dGPU and SSDs over to an older laptop. 😃 

 

I'm a bit surprised how expensive replacement motherboards are, even on ebay. (More than a used laptop with the same or better MB)  I guess the last MB i replaced in a laptop was for a M6800, which was fairly cheap but that was a socketed CPU.

[strigi]

On 9/13/2022 at 10:39 AM, Aaron44126 said:

I believe 7710 motherboards are compatible.  Find some photos and check the screw hole positions and make sure that they are the same, and you should be good.  (I know a couple of users upgraded Precision 7510 to 7520 by swapping out the motherboard.  I don't remember hearing about the 77X0 systems but I'd think it would be the same.)

 

Most stuff should be compatible but under Windows you'd need a NVIDIA INF mod to get a Pascal GPU to work.

 

Regarding the issue...  With just the top bullet, I'd suggest trying a different PSU if you haven't already.  But with that other stuff, and given that you've already replaced the battery...  Yes, I'm worried about your motherboard.

 

I have had the reverse problem - something power related on my 7710 failed, and at the time it was cheaper to source a 7720 motherboard. I recall being able to more or less drop in the 7720 motherboard and the screw holes lined up. (In fact, that is how I found NBR in the first place, to see if that doable!)

 

One other thing to consider is that your original daughterboard/IO boards may not match up on the connector. I had an older 7710 pre-Thunderbolt port, so the left side IO board needed to be changed to match the 7720 that had it. However, I also ended up having to change the right side board as well, even though the port layout is the same (I believe). I think electrically the pinout worked, but in my case the plastic guides for the connection were shaped slightly differently and so I got a replacement right side board too.

 

I'm not sure if any of this is relevant if you get a 7710 motherboard with the Thunderbolt port.